Transflective display device

ABSTRACT

A transflective FPD device is provided. The transflective FPD device includes a liquid crystal layer and a transflective layer. The transflective layer includes a matrix made of a transparent material and a plurality of reflective nano-particles. The reflective nano-particles are configured for reflecting ambient light and are dispersed uniformly and randomly in the entire matrix. The transflective layer is adapted for reflecting ambient lights, and as well as for allowing backlight to pass therethrough.

CROSS-REFERENCES TO RELATED APPLICATION

This application is related to a copending U.S. patent applicationentitled “A TRANSFLECTIVE DISPLAY DEVICE” with the same assignee. Thedisclosure of the above-identified application is incorporated herein byreference.

1. Field of the Invention

The present invention relates to a transflective display device and,particularly, to a transflective flat panel display (FPD) device.

2. Description of Related Art

Conventional FPD devices are generally classified into reflectivedevices and transmissive devices. A transmissive FPD device displays animage by using light emitted from a backlight source, and a reflectiveFPD displays an image by using ambient light.

A transmissive FPD device is capable of producing a bright image with ahigh contrast ratio without being substantially influenced by thebrightness of the environment, but such a device consumes a lot of powerdue to the backlight. Moreover, a transmissive FPD device has a poorvisibility under very bright environments (e.g., when used outdoor undera clear sky).

On the other hand, a reflective FPD device consumes little power, butthe brightness and the contrast ratio thereof are liable to beinfluenced by the conditions, under which it is used, e.g., thebrightness of the environment. Particularly, the visibility lowerssignificantly under dark environments.

In order to overcome these problems, transflective FPD devices, whichare capable of operating both in a reflection mode and in a transmissionmode, have been proposed in the art.

A conventional transflective FPD device typically employs atransflective layer having a typical so-called multi-gap structure. Themulti-gap structure is composed of a plurality of reflective meansdistributed separately, each two of which defines a transmissive gaptherebetween. The reflective means are adapted for taking advantages ofambient light, while the gaps are adapted for allowing backlight passagetherethrough. However, since parts of the transflective layer aretransmissive and the others are not, a conventional transflective FPDusually has no way to give better attention to its transmission abilityand its reflection ability. Furthermore, the above-mentioned multi-gapstructure is generally disposed above a liquid crystal layer and a colorfilter layer. As a result, an FPD device having such a configurationtypically cannot provide a satisfactory color saturation.

Therefore, what is needed in the art is to provide a transflective FPDdevice giving better attention to its transmission ability and itsreflection ability and having a satisfactory color saturation.

SUMMARY OF INVENTION

According to the present display, a transflective FPD device isprovided. The transflective FPD device includes a liquid crystal layerand a transflective layer. The transflective layer includes a matrixmade of a transparent material and a plurality of reflectivenano-particles. The reflective nano-particles are configured forreflecting ambient light and are dispersed uniformly and randomly in theentire matrix.

An advantage of the FPD device is that the reflective nano-particlesprovide better and more efficient reflection, and thus less reflectionarea is needed and more transmission area can be used for transmittingthe backlight.

Another advantage of the FPD device is that the transmission/reflectionratio of the transflective layer can be determined by controlling thequantity, size distribution, and reflectivity of the reflectivenano-particles.

A further advantage of the FPD device is that better color saturationcan be obtained by appropriately designing the reflective nano-particlesize distribution.

A still further advantage of the FPD device is that the transflectivelayer can be integrated as a whole into a thinner substrate, thus savingproduction cost.

BRIEF DESCRIPTION OF DRAWINGS

The above-mentioned and other features and advantages of the presenttransflective display device, and the manner of attaining them, willbecome more apparent and the invention will be better understood byreference to the following description of its embodiments taken inconjunction with the accompanying drawings.

FIG. 1 is a schematic, cutaway view of an FPD device, according to anexemplary embodiment;

FIG. 2 is a schematic, cross-sectional view of a transflective layer ofthe FPD device of FIG. 1; and

FIG. 3 is a schematic, partial cross-sectional view showing atransflective layer, according to another exemplary embodiment.

Corresponding reference characters indicate corresponding partsthroughout the several views. The exemplifications set out hereinillustrate at least one preferred embodiment of the presenttransflective display device, in one form, and such exemplifications arenot to be construed as limiting the scope of such a device in anymanner.

DETAILED DESCRIPTION

Reference will now be made to the drawings to describe the preferredembodiments of the present FPD device, in detail.

Referring now to the drawings, and more particularly to FIG. 1, there isshown a transflective FPD device 100. The transflective FPD device 100mainly includes an upper substrate 102, a lower substrate 104, a liquidcrystal layer 110, a transflective layer 120, a thin film transistor(TFT) layer 130, a color filter layer 140, an upper polarizer 162, and alower polarizer 164.

The liquid crystal layer 110 is interposed between the upper substrate102 and the lower substrate 104 and includes a plurality of liquidcrystal molecules. The liquid crystal layer 110 further includes anupper alignment film 112, and a lower alignment film 114. The liquidcrystal molecules are received between the upper alignment film 112 andthe lower alignment film 114. The upper alignment film 112 and the loweralignment film 114 are adapted for aligning the liquid crystal moleculesto control the passage of light therethrough. The transflective layer120 and the color filter layer 140 are interposed between the liquidcrystal layer 110 and the lower substrate 104. The transflective layer120 is disposed adjacent the lower substrate 104. The color filter layer140 is disposed adjacent the liquid crystal layer 130. The color filterlayer 140 is disposed on the transflective layer 120. The transflectivelayer 120 is adapted/configured for allowing backlight to transmittherethrough and to then be incident onto the liquid crystal layer 110and is further adapted/configured for allowing environmental light bereflected back to the liquid crystal layer 110. The TFT layer 130 isinterposed between the upper substrate 102 and the liquid crystal layer110 and is configured for driving the FPD device to display, e.g., aparticular image and/or set of alphanumeric characters. The upperpolarizer 162 and the lower polarizer 164 are respectively adapted forproviding polarized lights for displaying.

In the illustrated exemplary embodiment, the transflective FPD device100 further includes an upper ½ wave plate 152, an upper ¼ wave plate154, a lower ¼ wave plate 156, and a lower ½ wave plate 158. The upper ½wave plate 152 and the upper ¼ wave plate 154 are interposed between theupper substrate 102 and the upper polarizer 162, while the lower ¼ waveplate 156 and the lower ½ wave plate 158 are interposed between thelower substrate 104 and the lower polarizer 164. The positions of theupper ½ wave plate 152 and the upper ¼ wave plate 154 areinterchangeable, and the positions of the lower ¼ wave plate 156 and thelower ½ wave plate 158 are also interchangeable. The wave plates 152,154, 156 and 158 are adapted for complementing a phase delay of thetranflective FPD device 100. It is to be noted that other phasecomplementary components can also be employed, additionally oralternatively, to perform such a function.

Furthermore, the transflective FPD device 100 may further include ananti-glare coating layer 170 and an anti-reflection coating layer 180.The anti-glare coating layer 170 is disposed on the upper polarizer 162for eliminating or at least limiting glare caused by excessive strongambient light. The anti-reflection coating layer 180 is disposed on theanti-glare coating layer 170 for allowing more light having a givenwavelength band to pass therethrough.

FIG. 2 illustrates an exemplary embodiment of the transflective layer220. The transflective layer 220 includes a plurality of reflectivedomains 224 configured for reflecting ambient light for displayillumination and further includes a plurality of transmissive domains222 configured for transmitting backlight for facilitating appropriatelighting of the display device. Each of the reflective domains 224includes a plurality of reflective nano-particles distributed therein,thereon, and/or thereunder adapted for enhancing a reflecting abilitythereof. In other words, the nano-particles can either bedoped/implanted into the reflective domains 224 and/or coated/depositedonto at least one surface of each of the reflective domains 224.Preferably, each of the reflective domains 224 has a plurality ofreflective nano-particles dispersed uniformly but randomly in the entirereflective domain 224 and/or on at least one surface of reflectivedomain 224. The nano-particles can, for example, be comprised of amaterial selected from a group consisting of Ag, Al, Ti, Cr, and Al—Agalloy.

An appropriate distribution of sizes of the reflective nano-particle canresult in a better color saturation. Sizes of the nano-particles are,for example, in the range from approximately 2 nm to approximately 2000nm and preferably in either about in a range from 5 nm to 20 nm or aboutin a range from 300 nm to 1200 nm. Smaller reflective nano-particlesshould be very densely distributed, such that the reflectivenano-particles can effectively cooperate with each other to reflect theambient light. Each larger reflective nano-particle can workindependently for reflecting the ambient light, and therefore largerreflective nano-particles can be distributed relatively sparsely.

For example, in a case of a single reflective domain 224, the sizes ofthe reflective nano-particles are distributed approximately in threedifferent ranges, i.e. a first range, a second range and a third range.The reflective nano-particles with sizes in the first range are adaptedfor reflecting lights (i.e., light wavelengths) in the red light band.The reflective nano-particles with sizes in the second range are adaptedfor reflecting lights in the green light band. The reflectivenano-particles with sizes in the third range are adapted for reflectinglights in the blue light band. The transmission/reflection ratio of thetransflective layer 320 is determined by adjusting the quantity, sizedistribution, and reflectivity of the reflective nano-particles.Therefore, ideal color performance for the FDP 100 can be achieved byadjusting the quantity, size distribution and reflectivity of thereflective nano-particles.

The transflective layer 220 includes a matrix made of a transparentmaterial and a plurality of reflective nano-particles distributedthereon or therein. Although the reflective domains 224 aresubstantially reflective, they may still allow some portions ofbacklight to pass therethrough. The reflective nano-particlesdistributed therein, thereon, and/or thereunder are randomly dispersed.Such reflective nano-particles are adapted for diffusely reflectingincident light from all directions and are adapted for scattering somebacklight that is incident thereon. Furthermore, the reflective domains222 are preferably configured in a given pattern and have either along-distance and/or a short-distance order.

Another exemplary transflective layer 320, as shown in FIG. 3, isdescribed as follows. The transflective layer 320 has a matrix and aplurality of reflective nano-particles incorporated therein, forreflecting ambient light. The reflective nano-particles are disperseduniformly and randomly in the entire matrix of the transflective layer320 and/or on at least one surface of the matrix of the transflectivelayer 320. When backlight is incident onto the transflective layer 320,the backlight is allowed to pass through the parts where few or none ofthe reflective nano-particles are distributed thereat and is thenscattered by the reflective nano-particles in the areas where suchnano-particles are more plentiful. When ambient light is incident ontothe transflective layer 320, they are diffusely reflected back to theliquid crystal layer with the aid of the reflective nano-particles.

An appropriate distribution of sizes of the reflective nano-particle canbe adjusted according to different practical situations so as to obtaina better color saturation. For example, sizes of the nano-particles canbe discretely distributed. The discrete distribution of thenano-particles would have at least one peak and preferably three peaks,each peak corresponding to a concentrated range of nano-particle sizes.The three peaks, for example, would correspond to a first range, asecond range and a third range. The reflective nano-particles with sizesin the first, second, and third ranges would be adapted for reflectinglights (i.e., light wavelengths) in the red, green, and blue lightbands, respectively. The transmission/reflection ratio, as well as thecolor performance, of the transflective layer 320 is determined or maybe adjusted by adjusting the quantity, size distribution, and/orreflectivity of the reflective nano-particles. It is to be noted thatalthough three peaks are exemplarily illustrated herein, more or lesspeaks may be optionally selected in the application of the presentdisplay device by those skilled in the art and be within the scopethereof.

The foregoing transflective layer 220 or 320 is preferably formed on thelower substrate 104. The transflective layer 220 or 320 mayalternatively be integrated as a whole with the lower substrate 104. Forexample, the lower substrate 104 of FIG. 1 can be doped/implanted and/ordisposed/coated with a plurality of reflective nano-particles to formeither a transflective layer 220, shown in FIG. 2, or a transflectivelayer 320, shown in FIG. 3. Such a lower substrate 104 may then functionsubstantially as the transflective layer 220 or 320.

It is of an advantage that the transmissive reflective layer 120 canprovide uniformly scattered and reflected light to the liquid crystallayer 110 for displaying. Similarly, it is of another advantage that thereflective domains 224 of the reflective layer 120 have a betterreflectivity. It is of a further advantage that the reflective layer 120can provide better color saturation.

While this invention has been described as having a preferred design,the present invention can be further modified within the spirit andscope of this disclosure. This application is therefore intended tocover any variations, uses, or adaptations of the invention using itsgeneral principles. Further, this application is intended to cover suchdepartures from the present disclosure as come within known or customarypractice in the art to which this invention pertains and which fallwithin the limits of the appended claims.

1. A transflective LCD device comprising: a liquid crystal layer; and atransflective layer comprising: a matrix made of a transparent material;and a plurality of reflective nano-particles configured for reflectingambient light, the reflective nano-particles having grain sizes in theapproximate range from 2 nm to 20 nm, said reflective nano-particlesbeing dispersed uniformly and randomly in the entire matrix.
 2. Thetransflective LCD device as described in claim 1, wherein the sizes ofsaid reflective nano-particles are discretely distributed.
 3. Thetransflective LCD device as described in claim 2, wherein the discretedistribution of said nano-particles has three peaks respectivelycorresponding to a first range, a second range, and a third range,wherein said reflective nano-particles with sizes in the first range areadapted for reflecting light of a red light band, said reflectivenano-particle with sizes in the second range are adapted for reflectinglight of a green light band, and said reflective nano-particles withsizes in the third range are adapted for reflecting lights of a bluelight band.
 4. The transflective LCD device as described in claim 1,wherein said reflective nano-particles are at least one of doped andimplanted into said matrix.
 5. The transflective LCD device as describedin claim 1, wherein said reflective nano-particles are randomlydispersed and are adapted for diffusely reflecting incident lights fromall directions.
 6. The transflective LCD device as described in claim 1,further comprising a color filter disposed under the liquid crystallayer.
 7. The transflective LCD device as described in claim 1, whereinthe reflective particles are comprised of a reflective material selectedfrom the group consisting of Ag, Al, Ti, Cr, and Al—Ag alloy.
 8. Thetransflective LCD device as described in claim 1, further comprising anupper polarizer disposed on the liquid crystal layer and a lowerpolarizer disposed under the transflective layer.
 9. The transflectiveLCD device as described in claim 8, further comprising an anti-glarelayer coated on the upper polarizer.
 10. The transflective LCD device asdescribed in claim 9, further comprising an anti-reflection layer coatedon the anti-glare layer.